Call Java method from c/c++ from native thread

Hi,
I know how to call a method from c/c++ with jni back to Java
but this fails when I try to do this from a native thread.
I can get the object class (jclass) but its seems to fail to get a method from that class.
How to make it work?
Thanks in advance.

Ok, problem has been solved
I just get the jmethodID inside a JNI method and pass it to the thread.

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In JNI how to call Java methods from native language methods

I just build the example of java tutorial on
http://java.sun.com/docs/books/tutorial/native1.1/implementing/method.html
but when I excute, it says:
Callbacks.c:1:syntax error before 'void'
Callbacks.c:2:parse error before '*'
Callbacks.c:In function 'Java_Callbacks_nativeMethod':
attached:
Callbacks.c
JNIEXPORT void JNICALL
Java_Callbacks_nativeMethod(JNIEnv *env, jobject obj, jint depth)
jclass cls = (*env)->GetObjectClass(env, obj);
jmethodID mid = (*env)->GetMethodID(env, cls, "callback", "(I)V");
if (mid == 0) {
return;
printf("In C, depth = %d, about to enter Java\n", depth);
(*env)->CallVoidMethod(env, obj, mid, depth);
printf("In C, depth = %d, back from Java\n", depth);
Callbacks.java
class Callbacks {
private native void nativeMethod(int depth);
private void callback(int depth) {
if (depth < 5) {
System.out.println("In Java, depth = " + depth + ", about to enter C");
nativeMethod(depth + 1);
System.out.println("In Java, depth = " + depth + ", back from C");
} else
System.out.println("In Java, depth = " + depth + ", limit exceeded");
public static void main(String args[]) {
Callbacks c = new Callbacks();
c.nativeMethod(0);
static {
System.loadLibrary("MyImpOfCallbacks");

Looks like you havn't included the jni header file. Add this to the top of the .c file:
#include "jni.h"

How to call java method from C ?

Hello,
I try to call a native method from java which calls java method from the same class. Exception (noSuchMethodError) is thrown. Any ideas?
Thanx in advance !
here is the source of the native method :
JNIEXPORT jint JNICALL Java_TestDll_Proc_1Mul_1Int_1Var_1Var_1Stdcall (JNIEnv * env, jclass jcl, jint jarg1, jint jarg2) {
int arg1;
int arg2;
int arg3;
jint res;
char * ch = "test";
jfieldID fid;
jmethodID mid;
int (* procedure) (int *, int * ,int *);
int mch;
arg1 = (int )jarg1;
arg2 = (int )jarg2;
procedure = GetProcAddress(libraryHandle,"Proc_Mul_Int_Var_Var_Stdcall");
procedure(&arg1,&arg2,&arg3);
res = (jint) arg3;
printf("(*env)->GetMethodID(env, jcl, \"test\", \"()V\");\n");
mid = (*env)->GetMethodID(env, jcl, "test", "()V");
printf("(*env)->CallVoidMethod(env, jcl, mid);\n");
(*env)->CallVoidMethod(env, jcl, mid);
return res;
here is the source of the java file:
public class TestDll {
static {
System.loadLibrary("testdllwrap");
System.out.println("java: Library testdllwrap.dll loaded");
public TestDll() {
public native int Proc_Mul_Int_Var_Var_Stdcall(int jarg1, int jarg2);
public void test() {
System.out.println("java: test()");
public static void main(String[] args) {
TestDll access = new TestDll();
int a = 5;
int b = 6;
int c = 0;
System.out.println("Calling Proc_Mul_Int_Var_Var_Stdcall");
c = access.Proc_Mul_Int_Var_Var_Stdcall(a,b);
System.out.println("Java Result = " + c);

Something is wrong with the code you posted here.
Since your native method is not static, it should have the jobject instance as a parameter in the function prototype, not a jclass. Also, you should be calling CallObjectMethod with a jobject, not jclass.
Check out Jace at http://jace.reyelts.com/jace.
To call the java method you would do:
JNIEXPORT jint JNICALL Java_TestDll_Proc_1Mul_1Int_1Var_1Var_1Stdcall
(JNIEnv * env, jobject jTestDll, jint jarg1, jint jarg2) {
TestDll testDll( jTestDll );
testDll.test();
}God bless,
-Toby Reyelts

How to call Java method from XSLT??

Hi All,
Jdev 11.1.1.3.0
I have a requirement to implement that, I have to call Java method from XSLT. Could anyone please suggest to implement that??
Thanks,
Santosh M E

As pointed by others, you must expose your method as a custom function, registering with JDeveloper (for development time) as well as with SOA Suite (for runtime).
In the link below you will find a simple step by step example:
https://blogs.oracle.com/reynolds/entry/building_your_own_path
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Hi
I have a requirement of updating field value 'Document Status' based on review/approve of content from Workflow and hence need to update the version number. For that I need to call my java method from workflow during submit of review/approve condition. Please let me know how to call java method from workflow?
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Sarang

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Now, the question is what are its arguments. It has two - the first is the name of a custom metadata field to be updated (let's suppose that one field is called xMinorVersion, and the other xMajorVersion), the other is the new value, e.g. <$wfUpdateMetaData("xMinorVersion", "New value.")$>As for new value - do you insist on using strings? Since you want to increase the value, it would be more convenient to work with numbers. For instance, with integers you could go with <$wfUpdateMetaData("xMinorVersion", xMinorVersion + 1)$>With strings you will need to convert it to numbers and back to strings. Besides, what happens if you have more than 100 minor versions? (you mentioned you want to add 0.01, but that would finally increase the major version, wouldn't it?) So, I think these two numbers are independent (perhaps, with exception that increase on the major version set the minor version to .00).
If you want to present it, you can use profiles that will construct for you the representation 2.304 out of MajorVersion = 2, MinorVersion = 304
Solved?

Call Java Method From JavaScript Function

hi everyone
i need a help in calling Java method from a javaScript method
ex:
function confirmAddRecord() {
cHours =document.getElementById('frmP:ChargeHours').value;
cSTime =document.getElementById('frmP:ChargeStartTime').value;
var answer = confirm("Are you sure you want to add Record?")
if (answer){
here i want to call the Java Method that is located in session bean that takes the upper params cHours & cSTime
else{
return false;
i know i can do it as an action button but it is required me to be in that way can any one help plz
Message was edited by:
casper77

That depends on the nature of your parameters. I guess you calculate the params on client and then want to submit them. In this case and if you don't want to use Ajax simple add some <input type="hidden"> elements (of course there correspondend components dependent of your framework) and store the params there. If the javascript isn't invoked by a button click, you can use a button nevertheless. Set visible="false" and call
document.getElementById('client_id_of_my_hidden_button').click();
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Calling Java methods from C program

After a year or so using these excellent forums to answer my queries, without ever having to post a question, I've finally had to ask for help with this one. I've already looked through the JNI tutorial, and these forums, extensively, but I'm still not quite sure of how best to solve my problem.
I need to call Java methods from a C program. I've already used JNI to call a simple C program from Java, and that's fine, but I just can't determine exactly what I need to do for the reverse to work.
What is the definitive solution for calling Java from C? Is it to use the invocation APIs to create a JVM, and then access it through the various GetMethod, FindClass methods? Or can I 'reverse engineer' the process I followed to get Java to call C?? The tutorial is a bit confusing, as the example it gives uses Callback stuff, but I guess that's only useful when you want to go Java-C-Java??
Advice appreciated,
Rich

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null

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pname is the name for a parameter to procname
mode is the parameter mode (i.e. IN, OUT, IN OUT)
ptype is a valid SQL type (e.g. NUMBER, CHAR, etc.)
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javatype is a Java type for the corresponding parameter
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sensitive. For example, if the keyword 'return' is in all
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Other optional parts of this syntax have been omitted here for simplicity.
Additional examples in subsequent sections illustrate some of these options.
eg
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available in Java. OUT parameters, therefore, must be passed as single
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of VARCHAR2 or CHAR type IN parameters. For example, the java method:
public static void main ( String[] args ) { ... }
can be mapped to each of the following:
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null

How to call Java methods from a Windows application?

Hello all,
At our company, we need to integrate our product which is a Java Swing application with a Windows application. Specifically, we are trying to call Java methods that reside in our application from the Lotus Notes email client application, which is a native Windows application. Such that when a user clicks a button in the Lotus Notes email client, it will trigger an event in our Swing application. Is this possible using JNI? Do you know of any resources or references relating to this kind of a project?
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Problem calling java method from c

Hi ,
I'm trying to call a java method from a C program. it gives no error during compilation as well as building the application. but when i tried to create the JVM by running my application it pops up the message "The application failed to start because jvm.dll was not found. Re-installing the application may fix the problem." I tried out setting all the environment variables to include the jvm.dll(PATH set to c:\j2sdk1.4.2_05\bin;c:\j2sdk1.4.2_05\jre\bin). Still got the same message. Then i re-installed java platform once more. Even now i get the same error. I have more than one jvm.dll at locations jre\bin\client and server, oracle has some jvm.dll . Will that be a problem? if so can i remove those? which of them should be removed and how?
The code i'm using is
#include <stdio.h>
#include <jni.h>
#include <windows.h>
//#pragma comment (lib,"C:\\j2sdk1.4.2_05\\lib\\jvm.lib")
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JNIEnv env; / Pointer to native method interface */
JDK1_1InitArgs vm_args; /* JDK 1.1 VM initialization requirements */
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FARPROC JNU_FindCreateJavaVM(char *vmlibpath)
HINSTANCE hVM = LoadLibrary("jre\\bin\\server\\jvm.dll");
if (hVM == NULL)
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void main(int argc, char **argv )
JavaVM jvm = (JavaVM )0;
JNIEnv env = (JNIEnv )0;
JavaVMInitArgs vm_args;
jclass cls;
jmethodID mid;
jint res;
FARPROC pfnCreateVM;
JavaVMOption options[4];
// jint (__stdcall pfnCreateVM)(JavaVM *pvm, void **penv, void *args) = NULL;
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options[1].optionString = "-Djava.class.path=c:/j2sdk1.4.2_05/jre/lib/rt.jar"; /* user classes */
options[2].optionString = "-Djava.library.path=lib"; /* set native library path */
options[3].optionString = "-verbose:jni"; /* print JNI-related messages */
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vm_args.version = JNI_VERSION_1_4;
vm_args.options = options;
vm_args.nOptions = 4;
vm_args.ignoreUnrecognized = 1;
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pfnCreateVM = JNU_FindCreateJavaVM("jre\\bin\\server\\jvm.dll");
res = (*pfnCreateVM)(&jvm,(void **) &env, &vm_args );
// res = JNI_CreateJavaVM(&jvm,(void **) &env, &vm_args );
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cls = (*env)->FindClass( env, "InstantiatedFromC" );
if ( verbose )
printf ( "Class: %x" , cls );
/*jvm->DestroyJavaVM( );*/
Could anyone help me solve this problem as early as possible, bcoz i'm in an urge to complete the project.
Thanks in advance.
Usha.

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Call Java Method from Callback function

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jschell wrote:
JNI parameters? Meaning what exactly?
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1. Entry
2. Get the VM, env - there are methods for this
3. Attach the thread
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void MyClass::onEvent(int system_id, char* data)
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     JNIEnv *env;
     jvm->AttachCurrentThread((void **)&env, NULL);
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}My last question is about cleanup in this function. When I use NewStringUTF to "convert" my char* to jstring do I need to do anything special to clean up or will the Java garbage collector take care of it since the jstring is being passed to a Java method?
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Hi,
I have defined a java class with set of methods , and I want to know if there is any way to call those methods from a BPM process..
Thanks in Advance,,
Best Regards,,
Ola Essa..

Use the spring component context in soa suite instead of ejb. Look for documentation in soa suite developer guide. Only if you have existing ejbs then use ejb adapters.
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Vikram
Message was edited by: VikramFusionApplied

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hi friends,
How to call a java method from xsl, i have a xsl file which will call the java method and retrieve the value and display it to the user. but its work well when i set xalan.jar and xerces.jar and the java class files in my classpath and run as
java org.apache.xalan.xslt.Process -in navigate.xml -xsl nav-exst.xsl -HTML -out navoutpage.html[b]
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OK. So, I think we can all conclude that you don't need to call any Java method, can't we? And, that wfUpdateMetadata is the command that will update your metadata.
Now, the question is what are its arguments. It has two - the first is the name of a custom metadata field to be updated (let's suppose that one field is called xMinorVersion, and the other xMajorVersion), the other is the new value, e.g. <$wfUpdateMetaData("xMinorVersion", "New value.")$>As for new value - do you insist on using strings? Since you want to increase the value, it would be more convenient to work with numbers. For instance, with integers you could go with <$wfUpdateMetaData("xMinorVersion", xMinorVersion + 1)$>With strings you will need to convert it to numbers and back to strings. Besides, what happens if you have more than 100 minor versions? (you mentioned you want to add 0.01, but that would finally increase the major version, wouldn't it?) So, I think these two numbers are independent (perhaps, with exception that increase on the major version set the minor version to .00).
If you want to present it, you can use profiles that will construct for you the representation 2.304 out of MajorVersion = 2, MinorVersion = 304
Solved?

Call Java method from c/c++ from native thread

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